Numerous processes are known for the preparation of toners, such as, for example, conventional polyester processes wherein a resin is melt kneaded or extruded with a pigment, micronized and pulverized to provide toner particles of the desired volume average particle diameter and geometric size distribution. In such processes, wherein large materials are mechanically reduced in size to achieve the desired smaller toner particles, it is usually necessary to subject the aforementioned toners to a classification procedure such that the desired size and geometric size distribution are attained.
As an improvement to the foregoing mechanical reduction processes, processes are known in which the toner is achieved via aggregation as opposed to particle size reduction. For example, chemical aggregation processes for the preparation of toners are illustrated in a number of patents. In these methods, the toners are formed chemically in situ and do not require known pulverization and/or classification methods.
Methods for forming toners by the chemical aggregation process have included the process described in Toth et al., U.S. Pat. No. 6,395,445 B1, where the aggregating agent is added as a solution in water, particularly a dilute solution of the aggregating agent. While advantageous in embodiments, the use of a dilute solution of the aggregating agent may possibly limit the throughput in the reactor vessel due to the volume taken up by the solvent. Thus there is a need addressed by the present invention for new processes that can add the aggregating agent either alone or in a solution or mixture, thereby increasing the flexibility of the new processes in adding aggregating agents regardless whether such aggregating agents are dissolved or dispersed in a liquid.
Other documents that may be relevant to the present invention are the following:
Sacripante et al., U.S. Pat. No. 5,593,807;
Sacripante et al., U.S. Pat. No. 5,348,832;
Patel et al., U.S. Pat. No. 5,723,252;
Durrwachter, U.S. Pat. No. 5,910,595;
Mychajlowskij et al., U.S. Pat. No. 5,660,965;
Patel et al., U.S. Pat. No. 5,994,020;
Mychajlowskij et al., U.S. Pat. No. 5,945,245; and
Carlini et al., U.S. Pat. No. 6,143,457.
The present invention is accomplished in embodiments by providing a process comprising:
agitating a mixture including a liquid and a plurality of resin particles within a vessel at a first shear condition;
circulating a portion of the mixture from the vessel through a mixer;
adding not all at once an aggregating agent for the resin particles and mixing the aggregating agent with the circulating mixture portion within the mixer at a second shear condition more intensive than the first shear condition to result in a post-mixer circulating composition; and
returning the post-mixer circulating composition to the vessel wherein the post-mixer circulating composition undergoes the agitating at the first shear condition.
There is further provided in embodiments a process comprising:
agitating a mixture including water, a plurality of resin particles, and a colorant within a vessel at a first shear condition;
circulating 100% by volume of the mixture from the vessel through a mixer;
adding not all at once an aggregating agent for the resin particles and mixing the aggregating agent with the circulating mixture portion within the mixer at a second shear condition more intensive than the first shear condition to result in a post-mixer circulating composition; and
returning the post-mixer circulating composition to the vessel wherein the post-mixer circulating composition undergoes the agitating at the first shear condition.